Double Glazing Research Articles

Разработка и верификация имитационной модели процесса теплопередачи через оконный блок с теплоотражающими экранами

Window units account for the largest specific heat losses. The use of movable heat-reflecting screens and photovoltaic solar panels is of particular interest among the existing technologies to improve the thermal protection of windows. Despite the large number of scientific papers on this issue, which consider experimental laboratory studies and numerical simulation of heat transfer processes through window units, there is no data on the influence of the edge zones of a double-glazed window, as well as the areas of interface of the window profile and the light opening on the thermal processes that occur in these energy-saving units with screens. Vertical replacing of specific heat fluxes and temperature on the inner surface of the window unit strongly influences the correctness of determining the value of the minimum allowable temperature of the indoor air. Thus, the development and verification of models of the heat transfer process through a window unit with screens is an urgent task in the context of an indoor microclimate creation. Simulation numerical modeling is performed using the finite element method based on the fundamental laws of heat transfer. The authors have used the results of experimental studies of windows with heat-reflecting screens carried out in a certified climatic chamber. The authors have developed a two-dimensional simulation model of heat transfer through a window unit with heat-reflecting screens located in the partition wall of the climate chamber. The distribution of temperatures, air flow velocities, and reduced total thermal resistance along the height of a translucent structures has been studied. The adequacy of the proposed simulation model is confirmed by comparison with the results of the experiment in a certified laboratory, as well as data obtained by other authors and regulatory documentation. The use of heat-reflecting screens in the window unit increases the resistance to heat transfer by 1,6–3,7 times depending on their number. A significant decrease in temperature in the edge zones of the double-glazed window is revealed. The use of the developed simulation model makes it possible to determine the application of heat-reflecting screens in windows for intermittent heating systems including the case of using pre-drying air technology for humid, wet, or normal operation modes of industrial premises.

Optimizing greenhouse design: Effect of argon double glazing on climatic factors distribution and energy savings

The growing significance of covered crops in recent decades has prompted the establishment of objectives for greenhouse design and management, aiming to strike a balance between productivity and environmental sustainability. Specifically, ongoing efforts are focused on optimizing greenhouse design to enhance solar radiation absorption and maintain a stable temperature environment for crops throughout their growth period. This paper presents a study that utilizes TRNSYS 18 simulation and experimental validation techniques to investigate the impact of Argon Double Glazing (ADG) on the distribution and uniformity of climatic factors within the greenhouse. Additionally, an energy analysis was conducted, revealing that ADG has a positive influence on reducing heating and cooling requirements compared to other cover materials. The results demonstrate the high efficiency of ADG as a construction material for greenhouses, leading to a reduction in greenhouse production costs.

Smart double glazing integrated polymer dispersed liquid crystal for enhancing building's thermal performance in hot-arid climate

Polymer-dispersed liquid crystal glazing is an electrically activated smart switchable glazing that requires an AC power supply to become transparent and remains opaque without power. This dynamic feature, with multiple transparency states, is suitable for building in hot and arid climates. It can effectively reject unwanted solar energy, allowing visible light while contributing to building energy efficiency by reducing the carbon footprint. In this work, the PDLC glazing system was included with a low-e coated glass and this coupled system was investigated with two control approaches for residential buildings in hot arid climates. The first control is a standard On-Off operation based on the tenant preferences, while the second is able to set glazing transparencies according to the solar radiation intensity, in order to minimize the penetration of direct solar radiation and to provide daylighting and indoor privacy protection. The system is reversed to examine the proper positions and layer order in the glazing system. The proposed system demonstrates remarkable enhancements in indoor thermal performance, surpassing clear glass by 21 % in the south orientation and 25.5 % in the west orientation. Furthermore, when the PDLC is oriented towards the outdoor environment, the system achieves an impressive 53.9 % improvement in heat gain control compared to clear glass. Additionally, the system not only enables dynamic control over direct solar radiation but also offers efficient daylighting and indoor privacy protection.

Mitigating Overheating Risks for Modern Flats in London Due to Climate Change

With the increase in global temperatures, a significant threat of overheating has been reported due to more frequent and severe heatwaves in the UK housing stock. This research analyzes dwellings’ physical attributes through overheating assessments and their adaptation for modern flats in London in the current (2022) and anticipated (2050) weather. According to preliminary research, Southeast and London in England, mid-terraced, and flats (especially built post 2012), among other archetypes, were discovered to be the most susceptible to overheating in the UK. This study employed a case study of a 2015 modern flat located in a high-risk overheating zone in London to understand the building’s overheating exposure. A range of Dynamic Thermal Simulations (DTS) was conducted using EnergyPlus with reference to case studies in order to assess the performance of passive cooling mitigation strategies (PCMS) on peak summer days (15 July) as well as during the summer against CIBSE Guide A and ASHARE 55. Reduced window area and LoE triple glazing were identified as excellent mitigation prototypes, in which solar gains through exterior glazing were reduced by 85.5% due to triple glazing. Zone sensible cooling was reduced by 52%, which minimized CO2 emissions. It was also identified that the final retrofit model passed CIBSE Guide A by achieving a temperature threshold of 20 °C to 25 °C during the summer months, whereas it failed to accomplish the ASHARE 55 criteria (20–24 °C). The outcome of this study justifies the necessity of tested PCMS and advises UK policymakers on how to foster resilient housing plans to overcome overheating issues.

A cross-climate assessment of the visual and energy performance of flexible photochromic films for in-situ window retrofits

Driven by their low thermal resistance and static transmittance to solar radiation, existing static clear windows are often considered the least-efficient components in the building envelope, driving the heating and cooling demands and compromising the thermal and visual comfort of building occupants. Hence, window retrofit technologies that utilize innovative coatings are critical for enhancing energy efficiency and indoor daylight quality in the existing building stock. In particular, dynamic photochromic window films that reversibly modulate solar gains responding to the abundance of ultraviolet radiation are promising but received little attention. In this paper, five commercial flexible photochromic window films were experimentally characterized, and their energy and daylighting performance were numerically and parametrically evaluated in a representative office with different window configurations and orientations across six representative cities with a diverse range of climates. This is one of the first works dealing with photochromic window films as a retrofit technology. The results show that the films exhibit excellent colour-rendering and cyclic stability with rapid switching/bleaching rates. In addition, annual energy savings in the 1% − 4% range were observed for low window-wall ratios, reaching 10% − 14% in cooling-dominated climates with lower latitudes using PC-1, which resulted in the most significant cooling energy savings. Although the film influenced the quantity of light, resulting in lower daylight autonomy, improvements in the useful daylight illuminance and significant reductions in discomfort glare levels were the major benefits of retrofitting existing double-glazed clear windows with the photochromic film.

TOWARDS ACHIEVING SUSTAINABLE DEVELOPMENT GOAL-2030 AGENDA-THIRTEEN: SELECTIVE TREATMENT OF SUN-FACING RESIDENTIAL WINDOW FABRICS IN THE TROPICAL BUILDING DESIGN

High solar gains associated with the Tropical climate result in high indoor temperature, the consequence of which induces indoor thermal discomfort. Particularly, both the East and West facing component building envelope receive more solar gains through early morning sun rise and late afternoon sun set respectively, thereby raising the indoor temperature of the affected spaces within the periods. However, the need to optimize indoor thermal comfort through mechanical installations among others, increases carbon emissions into the atmosphere, as buildings account for about 40% of global emissions through their construction, operation and maintenance. Due to its importance at the global level, Climate Change induced mitigation has resulted into promulgation of seventeen-pronged (17) United Nation’s Sustainable Development Goal 2030 (SDG-2030) Agenda. Of particular relevance within the precinct of built environment is the Agenda thirteen (Agenda-13) which encompasses the need for urgent action to combat Climate Change and its impacts across various areas of human engagements. It is on this basis that this research work explored beneficial impacts of selective treatment of East and West-facing residential building window fabrics, in the tropical city of Ogbomoso, Nigeria. In its approach, comparative evaluations of indoor solar gains using single-glazed and double-glazed virtual building models was carried out through DesignBuilder based simulations. The results indicate 8.5%, 8.5% and 8.6% annual reductions in the indoor solar gains in the whole building, East-end apartment and West-end apartment respectively, with the adoption of the double-glazed windows. Focusing specific individual sun-facing functional spaces (bedrooms in this case), more significant reduction in the indoor solar gains (i.e., about 28%) was recorded in each case. This research output may influence subsequent design and composition of the sun-facing window fabrics at this local level, thereby leading to reduced mechanical installations, for optimum indoor thermal comfort. This is an attempt to contribute towards achieving SDG-2030 Agenda-13 individually at this level, for overall collective realization at the global level. This endeavour aims at reducing carbon emissions at the building micro level in the study area, for overall clean, safe and sustainable global environment. This submission is part of an ongoing research work scheduled to be validated with life prototype/physical models subsequently.

The challenge of rehabilitating relocated listed heritage Buildings: Requirements and opportunities

This study evaluates three listed farmhouses in Ørland Municipality which are going to be relocated and rehabilitated according to current Norwegian standards and requirements. Accordingly, the study assesses possible challenges and solutions regarding energy upgrading and restoration while preserving their historic features and cultural heritage. The study suggests solutions for the energy rehabilitation of the three farmhouses based on a literature review, hygrothermal simulations and energy simulations. These solutions include thermal post-insulation of external walls and above the framework of joists against the cold attics with mineral wool, vacuum insulation panels (VIP), and aerogel blankets. Additionally, fenestration renovation options and the potential for implementation of building integrated photovoltaics (BIPV) are reviewed. Lastly, simulations of multiple energy-saving measures for each of the farmhouses have been conducted.A new foundation due to the relocation, together with post-insulation of the cold attic are found to be feasible measures considering the preservation of architectural appearance and authenticity. Regarding the external walls, post-insulating externally is preferable for the farmhouses considering moisture issues and interior space savings. However, it is important to consider any possible loss of cultural heritage value. Alternatively, internal thermal insulation with aerogel blankets may be a feasible solution due to its high thermal resistance applying small thicknesses. The results show that in some cases, enhancing old original windows with a secondary glazing is an equally good solution compared to a total replacement of the windows, and is recommended for cultural preservation. Implementation of BIPV contributed to meet the net energy demand requirement. Nevertheless, it is recommended that the chosen BIPV systems resemble an accepted roofing material from the regulatory requirements, e.g., slates, to accommodate the building’s architectural aesthetics and authenticity.This study provides insight and recommendations for the rehabilitation of three listed traditional farmhouses in Trøndelag County, addressing energy efficiency while preserving their cultural significance. The findings show that it is possible to achieve today’s energy requirements when rehabilitating listed heritage buildings. Results from energy simulations show that a reduction in net energy demand between 55 % and 75% is possible, while it is essential to note that each building is unique, and a case-by-case approach is needed. Nevertheless, the findings can be applicable for a general energy upgrading of heritage buildings.

Investigation of the performance of a double-glazing solar distiller with external condensation and nano-phase change material

The solar still is a device that is simple in construction, easy to operate, and cheap in cost. However, the solar stills produce low amount of productivity. In this work, it was targeted that the solar still productivity is improved via using double-glazing with external condenser and nano-phase change material. These parameters are designed and chosen to achieve the aim of enhancing the evaporation and condensation processes of the solar still. Therefore, the impact of using various types of phase change materials (black marble and paraffin wax mixed with graphene nanoparticles) is also experimentally investigated. The tests' findings showed that employing double glazing raised the water and glass temperature of modified distiller by 1–6 °C and 5–20 °C higher than that of conventional solar distiller, respectively. Also, the modified distiller with double glazing covering had a 31.34 % lower productivity than the conventional distiller. Besides, using condenser with modified distiller improved the distillate by 23.59 % over that of the conventional distiller (2480 mL/m2·day for conventional distiller versus 3065 mL/m2·day for modified distiller with double glazing and condenser). Moreover, utilizing the black marble and nano-paraffin wax phase change materials in the modified distiller with double glazing and condenser improved the freshwater production by 83.33 % (4840 mL/m2·day for modified distiller versus 2640 mL/m2·day for conventional distiller) and 99.24 % (5260 mL/m2·day for modified distiller versus 2640 mL/m2·day for conventional distiller) respectively over that of the conventional distiller under the same conditions. Finally, the highest efficiency for modified distiller was achieved when using double glazing, condenser, and nano-paraffin wax phase change material, where it was 43.6 % compared to 30.5 % for the conventional distiller. These results demonstrate the effectiveness of the proposed modifications.

Ideal thermochromic smart window in a south-facing office room of China considering daylighting and energy performance

ABSTRACT Thermochromic (TC) smart window which allows modulating the transmission of solar heat energy and sunlight in response to environmental conditions has great potential for improving the building energy and daylighting performance simultaneously. In this study, the multi-objective optimization method is used to determine the ideal optical properties of TC windows. Parametric assessment is firstly conducted to investigate the influence of several crucial parameters. Multi-objective optimization is then carried out by applying Non-dominated Sort Genetic Algorithm-III, maximizing daylight availability and building energy efficiency. Finally, the decision-making of the Pareto frontier is performed to achieve the ideal TC windows in 32 representative cities in different climatic zones of China. Results demonstrate that increasing the luminous transmittance at low-temperature and decreasing luminous transmittance modulation ability are beneficial to daylighting and energy performance. Lower solar transmittance at low-temperature contributes to building energy savings in Beijing, Shanghai, Guangzhou and Kunming, except for Harbin. Higher solar transmittance modulation ability is desired for building energy efficiency. The optimum value for the transition temperature is in the range of 23.67–38.85°C. The building energy consumption can be reduced by 13.01%, and the desired daylighting hours can be improved by 8.90%, relative to the clear double-glazed windows.

The impact of window orientation, glazing, and window-to-wall ratio on the heating and cooling energy of an office building: The case of hot and semi-arid climate

Adopting suitable design strategies in buildings throughout the design stage provides increased energy-saving potential. In this study, factors influencing window design, such as the window-to-wall ratio (WWR) and window orientation, along with different glazing materials, are being investigated in the city of Kirkuk, Iraq for possible energy consumption reduction. The study presents a simulation-based analysis on a typical office building in the area; evaluating four WWRs, four orientations, and three window glazing materials, e.g., clear, gray, and theoretical, as well as single and double-glazed windows. The results indicate that minimum heating consumption could be achieved with double clear glass for south-facing windows if WWR was 100 %. For north-facing windows, minimum cooling consumption is achieved with double theoretical-197 glass with a 25 % WWR. These measures can be utilized by architects and construction managers to communicate information to customers in an understandable manner and make better window design decisions.

Towards Sustainable Indoor Thermal Comfort in the Tropical Building Design: Comparative Performance Analysis of Fixed External Shading Elements and Differential Window Glass Thermal Properties

Tropical region is characterised by high outdoor solar radiation and temperature. These radiations penetrate into the interior particularly through the window glazing, thereby raising the indoor temperature with a resultant effect on high cooling energy demand (for comfortable indoor living condition). Of the identified three sustainable approaches towards inhibiting direct incoming indoor solar penetration in the tropical city of Ogbomoso, Nigeria, this study, through computer-based simulation technique, compared performance effectiveness of varying design interventions on the window composition/material adopted. Through multiple/iterative building performance simulation tool, DesignBuilder, the methodology involves virtual model of a three-bedroom residential building, typical of the prevailing building typology in the study area. This particular model served as the experimental control model. Three (3) variants of the control model, each with either externally mounted shading devices on the building envelope, or improved thermally resistant multilayer window glazing (i.e., double glazing) or low-emissivity coated window glazing material, were generated for individual performance effectiveness evaluation. All the four models were subjected to a twelve-month simulation cycle, to experience a year-round thermal conditions and evaluations individually. The results show that double-glazing window installation proved to be the most effective approach, with about 13.1 % improvement (i.e., solar radiation inhibition) on the indoor thermal gains. This is followed by the externally mounted shading devices (i.e., 11.1 % improvement) and the least inhibition (i.e., 5.0 %) was observed in the case of low-emissivity coated window glazing material. Adoption of double or more layers of glass panes in window fabrication for controlling indoor solar radiation penetration is therefore advised. Alternatively, integration of external window shading elements could be adopted. This study is directed towards reduction of cooling energy consumption in tropical buildings through efficient and sustainable indoor cooling mechanism capable of inhibiting solar gains into the building, with a focus on the performance roles and composition of windows in particular.

Comparative simulations of an electrochromic glazing and a roller blind as controlled by seven different algorithms

The use of roller blind as a surrogate for a switchable glazing in a dynamic building environmental simulation is investigated. Seven different control algorithms were applied to simulations of both operations of the blind and of the switchable glazing. The configurations compared were an electrochromic glazing and a roller blind, the controllers used were rule-based, proportional-integral-derivative (PID), anti-windup PID (aPID) and a model predictive controller (MPC). Particular case studies were examined in the weather conditions of Dublin, Ireland to make comparisons of simulated energy savings and occupancy daylight comfort from the use of electrochromic glazing or a roller blind with those for a double-glazed window. The results suggest that previous studies that simulated electrochromic window as an integrated roller blind in a heating-dominated climate would have overestimated building energy loads, and depending on the controller used, overestimated occupancy daylight comfort.

Thermal performance of a novel double-glazed window combining PCM and solar control glass in summer

The integration of PCM into glazed envelope to enhance its thermal inertia has shown great energy-saving potential. However, this could bring indoor overheating in summer due to the insufficient heat insulation for solar radiation in pure PCM glazed units. This work proposed a composite double-glazed window incorporating PCM and solar control glass, and numerically investigated its thermal behaviors under sunny and cloudy conditions in summer of northern China. The effects of glass optical properties, involving absorption coefficient and refractive index, on the phase change cycling, indoor thermal comfort and building energy efficiency were analyzed. The results show that the increase of glass absorption coefficient facilitates the melting of PCM, but degrades the thermal comfort, even resulting in overheating risk on the sunny day. Moreover, as the absorption coefficient and refractive index of glass increase, the energy efficiency of PCM window equipped with solar control glass instead of general glass can be improved remarkably, and the influence of refractive index is more drastic than that of absorption coefficient. On the sunny day, the energy saving rate is 14.25% for the glass absorption coefficient of 160 m−1, which is 41.53% for the glass refractive index of 3.

Economic and Energy Analysis of the Operation of Windows in Residential Buildings in Poland

This article presents the results of the economic and energy analysis of the operation of five types of windows in residential buildings. The aim of this study was to determine (a) to what extent the construction and various insulation parameters of windows affect the operating costs of buildings, when using different heating systems, (b) to what extent the significant cost of purchasing windows with better insulation is compensated by lower building operation costs (heating and the lifecycle of windows), (c) how the temperature difference inside the building affects heat loss through windows and, as a result, heating costs when using different heating systems. Five types of windows were selected for detailed analysis: a double- and a triple-glazed PVC window, double- and triple-glazed wooden window, and triple-glazed aluminum window. When wooden double-glazed windows are replaced with aluminum windows, the return on investment occurs in just 2 to 4.4 years. It was also found that of the five types of windows tested, the total economic balance of the operation period is the most favorable for PVC windows, regardless of the type of glazing and the heating system. The operating costs of PVC windows in a model residential building are over 30% lower than in the case of wooden windows and almost 20% lower compared to aluminum windows.

ENERGYSIM: techniques for advancing building energy education through immersive virtual reality (VR) simulation

An important practice for reducing the effects of global warming is the design and construction of energy-efficient buildings. In design education, the full comprehension of thermal behavior in buildings based on their geometry and material composition is required. The complexity of energy simulation principles, vis-a-vis the number of elements that impact the energy loads, their linkages, and their relationships to one another all combine to make this a challenging subject to absorb. Virtual Reality (VR) provides an immersive way to learn the concepts of building energy responses; however, the development of VR applications for education is difficult due to the knowledge, skill, and performance resource-related gaps. Unoptimized VR applications can adversely impact learning if user experiences are broken due to performance lags. This research, therefore, explores VR as a teaching tool for building energy education while showcasing the development process toward a visually accurate simulation and performant application. We developed EnergySIM; a multi-user VR building energy simulation prototype of the famous Farnsworth House. Using this prototype, we document rigorously tested development workflows for improved VR game performance, high visual fidelity, and user interaction, the three key factors which positively contribute to user knowledge retention. The study combines menu-driven interaction, virtual exploration, and miniature model manipulation approaches with the aim of testing user understanding and knowledge retention. Highlighted results provide reduced barriers of entry for educators towards developing higher quality educational VR applications. EnergySIM showcases pre-simulated building exterior surface heatmaps response from four seasons (winter, summer, fall, and spring) alongside an all-year-round sun-hour scenario. Four different material pre-simulated scenarios (single glazing, double glazing, concrete, and wood) for interior atmospheric temperature mapping are also explored. Preferred interaction methods are documented by allowing users’ visual appraisal of alternative building materials based on insulation capacity or resistance to heat flow (R-value). The significance of this work lies in its potential to revolutionize how students, designers, and instructors approach building energy education in today’s world. EnergySIM provides a hands-on and visually engaging learning experience towards the enhancement of knowledge retention and understanding. It pushes the boundaries of development for visual fidelity using geometry/mesh modeling input from various software into game engines and optimizing game performance using the HTC Vive Pro Eye and Meta Quest Pro headsets.

REDUCED HEAT LOSS THROUGH WINDOW STRUCTURES

The results of theoretical and experimental studies of heat transfer through the window structures of the building are presented, the thermal characteristics of the windows are established and the level of heat loss realized through them is estimated. To determine the heat transfer resistance of two-chamber double-glazed units, numerical modeling of radiative-convective heat transfer is performed, taking into account the thermal conductivity of the gas layer between the glasses. Natural free convection of the gaseous medium in the double-glazed chambers occurs as a result of the temperature difference between the side glass surfaces of the chamber. Modeling is performed by numerically solving the system of fluid dynamics and energy equations for the air layer and glass. On the inner surfaces of the chambers, conditions of the fourth kind are set, which take into account the radiation and conductive components of the total heat flow coming from the glass surface. The results of simulation of heat transfer through double-glazed windows with ordinary glass indicate that about 60 % of heat is transferred by radiation. Therefore, an effective measure to reduce heat loss through windows is to reduce the radiation component of the total heat flow by applying a low-emissivity coating to the inner surfaces of the glass unit. This makes it possible to reduce the total heat flow (and, accordingly, heat loss to the environment) by 20–34 %, depending on the number of glass surfaces with this coating. Conducted independent experimental studies confirm the modeling results. In order to comply with the current requirements of state building regulations and to achieve the energy efficiency class of type C buildings (specific heat consumption for heating 1 sq. m of usable area is less than 75 kWh), for the climatic conditions of Kyiv, it is recommended to use double-chamber windows with two low-emission coatings with the formula of the glass unit: 4M1-10-i4M1-10-i4M1. Bibl. 22, Fig. 8.

Energy Audits and Energy Modeling as a Tool towards Reducing Energy Consumption in Buildings: The Cases of Two Multi-Unit Residential Buildings (MURBs) in Toronto

This research is based on an energy audit of two multi-unit residential buildings (MURBs) located in Toronto, Canada. Energy consumption (gas and electricity) data were extracted from the energy bills of the two buildings for a consecutive period of three years. The data were then normalized to account for variations in weather conditions. Conclusions were drawn from correlation analyses between kWh, cooling degree days (CDDs), and heating degree days (HDDs), which were then compared to the energy consumption benchmarks of MURBs within the GTA. An energy simulation using e-Quest v.3.64 was performed, utilizing the advantages of the e-Quest building modeling tool to create a virtual 3D model of the audited buildings. A baseline model was constructed to reflect the actual buildings and was used to simulate the outcomes and calculate the projected energy savings from window replacements with a higher energy efficiency than the existing ones. The simulation results revealed that triple low-E glazing outperformed single- and double-glass windows, achieving reductions of 38% and 34% in gas consumption, respectively. The building envelope simulations showed that enhancing insulation reduced gas consumption by 4%, while an insulation upgrade demonstrated no discernible savings. Reducing the window area by 20% (north/south sides) led to a 6% decrease in gas consumption, while a 30% reduction resulted in approximately 9% of energy savings.

Optimum fenestration characteristics in mediterranean Tunisian context: An energetic, economic and environmental (EEE) study

This paper aims to investigate the energy performance of several techniques integrated into the fenestration system of an office building. The first step was to compare the simulated and real energy consumption of a case study of an office building located in Tunis City. In a second step, the study explores the impact of a glazing retrofit solutions on annual energy saving. To determine the possible energy savings for the existing office building in various climatic zones, we performed several simulations, using the Design Builder software.For these zones, the optimum window-to-wall-ratio (WWR), ensuring a compromise between daylighting and energy consumption, is found to be 40%. Then, for the chosen WWR, we evaluated a retrofit process involving existing commercial technologies such as double-glazed insulated windows, as well as innovative technologies consisting of intelligent coating, in addition to passive techniques including several shading concepts.It is found that, the double-glazed window with outside reveal depth of 20 cm equipped with both low-emissivity (LoE) and electrochromic (EC) coatings ensures the lowest annual energy consumption. Besides, energy savings depends on the climate zone; it reaches 23% in hot climates (ZT3) and almost 20% in cold (ZT1) and temperate climates (ZT2). The possibility of using electrochromic coating was excluded following the economic study because of its exorbitant cost. In fact, this type of renovation can lead to payback periods of up to 74 years for the cases treated.The optimized window designs consist in using a double-glazing window with a LoE coating, an outside reveal depth of 20 cm, and as a shading system (Overhang). These designs save 8 to 20% of energy and reduce CO2 emissions by 6 to 10 kg CO2/m2 per year, with a payback period of less than 6 years depending on the climatic zone.

Experimental and numerical study of an energy-efficient building fenestration system with seasonal adaptability

Previous building-integrated solar thermal fenestrations were limited to the single function, either air heating or water heating. Thus, they failed to meet the seasonal thermal needs of buildings. To address this limitation, this paper proposed a novel building fenestration-integrated solar collector. This system is designed to harness solar irradiation on the fenestrations for air heating in winter and recover irradiation for water heating in summer, effectively addressing seasonal thermal demands and improving annual solar utilization efficiency. Firstly, the prototype of the proposed system was fabricated, and its thermal performance was tested. The experimental results indicated the thermal efficiency of 40∼50% for air heating and 39% for water heating. Subsequently, a mathematical model of the proposed system was developed and experimentally validated. Based on the validated model, a comparative performance analysis was conducted between the proposed system and double clear glazing. Additionally, the energy-saving potential and economic viability of the proposed system were predicted. Compared to double clear glazing, the proposed system exhibited a higher solar heat gain coefficient (SHGC) in air heating mode, lower SHGC in water heating mode, and lower U value at night. The prediction outcomes underscored the substantial energy-saving advantages conferred by the proposed system across diverse building types. The projected payback periods in subtropical and tropical regions were estimated to be around 2–4 years.

An assessment of the impact of building envelope design on the tradeoff between embodied and operating energy

The building envelope encompasses an important share of construction materials and may dictate the embodied energy in buildings. This paper performs parametric analysis to evaluate the affect of several envelope design parameters on the operational and embodied energy consumption of the building. These parameters include southern wall glazing ratio, northern wall glazing ratio, glazing type, and wall assembly. The wall assembly design variables in turn include interior insulation thickness, interior insulation material, exterior insulation material, exterior insulation thickness, and outmost layer material. The other parts of the wall assembly remained constant in all simulation runs. A single store residential building with 150 m2 built-up area is considered as a case study to perform calculations. Based on the simulation results, Increasing the glazing ratio in the southern and northern walls from 0 to 80% results in a 12.7% and 15.7% increase in the total energy consumption, respectively. Moreover, employing triple pane windows raises the embodied energy compared to the double pane windows by 27.5%. However, they result in a 4.44% reduction in total energy consumption due to their better thermal insulation properties. Finally simultaneous variation of the glazing ratio and wall assembly reveled the minimum possible total energy consumption during the life cycle of the building can be obtained by providing aerogel as insulation material with 100 mm thickness in the interior insulation layer and 60 mm in the exterior insulation layer, fiber cement panels as the outmost layer and triple pane windows.